Self-ballasting gaseous discharge lamp



W J DREMANN ETAL SELF-BALLASTING GASEOUS DISCHARGE LAMP Filed Dec. 16, 1949 Aug. 4, 1953 mw s mmm ww TEU R wwe .n TW A mm W0@ Patented ug. 4, 19513 Walter J. Dremann, North Warren, Robert E. Dunham, Warren,r Pa., assignors to Sun Ray Electric, Inc., Warren, Pa., a corporation of Delaware Application December 16, 1949, Serial No. 133,455

2 claims. l

The present invention relates to electrically operating a gaseous discharge device generallyl and more specifically to such devices which are self-ballasting, that is, which require no external reactor or current limiting device.

An object of this invention is to lower the overall cost of fluorescent lamp illumination by providing a lamp which operates without the auxiliary external reactor which is now in general use to limit the current flow through the lamp. Such external reactors or ballasts are heavy, bulky and costly.

Another object of the invention is to provide a source of visible or ultra-violet rays of conventional appearance and so designed that it can be manufactured by using the present production methods.

Other objects and features of the invention will become apparent when the following description is considered in connection with the annexed drawing which is a broken cross-sectional view of a lamp illustrating our invention, the view also including schematic Wiring connections.

iThe lamp of our invention comprises the usual glass envelope ID having therein a gaseous conductive atmosphere. The envelope III contains two lamentary cathodes II and I2 which cathodes are coated in the usual manner with thermionic emitting materials. In the usual manner one leaf from cathode II extends through a press I3 and is connected to an external terminal I4. In like manner a lead from one end of cathode I2 extends through press I5 and is connected to a terminal I6.

In accordance with our invention the opposite end of cathode I I is connected to a resistor I1 which is in turn connected by means of a lead passing through the press I3 to a terminal I8. The construction at the opposite end of the lamp is substantially similar, that is, the lower end of cathode I2 is connected to a resistor 20 which is in turn connected by a lead passing through the press I5 to a terminal pin 2I.

It will be noted that the terminals I5 and I6 are smaller than the terminals I8 and 2I. This is true because it is necessary that the l-amp be polarized in order to assure that the limiting resistors I'I and 20 are automatically placed in series as respects the operating current when the lamp is in operation and subsequent to its original ignition.

As is indicated in the diagram, the terminals I4 and I5 are connected by the leads 22 and 23 respectively to a conventional starter '24, and the terminals I8 and 2I are connected to the usual 110 volt lighting circuit.

It is preferable that the direct leads to thek cathodes II and I2 from terminals I4 `and I6, respectively, be insulated between the press and the cathode end inthe manner shown at I9. This insulating of the leads assures that there will be no arc-over within the tube between the leads connected to terminals yI4 and I8 or I6 an 2| as the case may be. f

The gaseous atmosphere preferred in the envelope of this tube is argon or krypton or a mixtureV thereof supplemented in the usual manner with a minute quantity of mercury vapor whichk is usually introduced in the form of metallic mercury. The cathodes II and I2 are usually coiled-coil filaments of tungsten coated with an electron-emitting substance such for example as barium and strontium oxides to which may be added calcium oxide and calcium carbonate.

The current limiting resistors I1 and 20 are preferably made of alloys of iron land chromium in order to reduce expense although they may be .made of high melting point material such as tungstenor molybdenum. The mechanical design of these resistors as well as their electrical properties are extremely important to the proper y functioning of our invention. y

`'I'he operation of this device is as follows. The lamp is put into use by closing of the usual manual switch in the volt supply line. The circuit is initially completed therefore through the resistor Il, cathode I I, starter 24, cathode I2 and resistor 20. The starter operates after a short period of time to open the connection between terminals I 4 and I6 and the arc then strikes across the lamp. During one-half cycle of the alternating current the current enters the lamp through the terminal I8, is limited in value by passing through the resistor I'I, and flows as an electron now from cathode I I through the conductive atmosphere of the gas to the point of highest opposite polarity in the lamp, namely, the right hand end of resistor 2U. On the following half-cycle current fiows through terminal 2 I, resistor 20, and thence across the lamp through the conductive gas to the point of highest potential at the other end of the tube, namely, the left end of resistor I'I.

In the design of resistors II and 20 it is important to achieve a balance between the overall length and the voltage across the resistor, in order that the voltage per inch across the resistor be less than the voltage per inch required to cause ionization of the gaseous atmosphere. If the voltage per inch were allowed to exceed the per inch voltage breakdown potential of the gas the current would bypass the resistor and would therefore not'be limited by the resistor, which would result in the destruction of the lamp.

Usually in a discharge device of this type the ballasting device is designed to absorb approximately 50 to 60% of the applied voltage. This voltage is the product of the current in amperes and the resistance in ohms of the series resistor and this product, divid'edby the eiective length of the resistor in inches, must be less than the breakdown potential of the gas in volts per inchconsidering the non-emissive character ofA the resistor metal.

The foregoing description is related to utilization of a gas discharge lamp in analternating v current circuit. It will of course be understood that a lamp of the same generalcharacter may be utilized on a direct current circuit in which event only one of the resistor elements would vbe necessary since the current flow would be in one direction only.

While we have described a preferred embodiment,l it will be understood that many modifications thereof are possible and we wish therefore not to be limited bythe foregoing description but on the contrary solely by the claims granted us.

What we claim is:

1'. Av fluorescent lamp comprising an elongated tubular envelope, a gaseous atmosphere in said tubular envelope, a lamentary electron emitting cathode at each end of the device within the envelope, a resistorv connected in series with each lamentary cathode, each resistor being positioned within the envelope adjacent its respective cathode, a pair of polarized terminal pins at each end of the envelope, the respective cathodes being directly connected to pins of one type and the resistors to pins of the other type, said lamp being adapted to insertion in a pair of polarized receptacles so that during an initial starting period the circuit extends through said cathodes and resistors in series and subsequently to the initial period the circuit extends through one of said resistors and its associated cathode, and thence through the arc discharge path to the end' of the opposite resistor furthest removed from the associated cathode, said resistors having a potential drop per unit of length less than the breakdown potential of the gaseous atmosphere per'unit of length, saidl resistors being alternately 4i in series with the discharge path and serving to limit the current through the lamp.

2. A iluorescent lamp comprising an elongated tubular envelope, a, gaseous atmosphere in said tubular envelope, a lamentary electron emitting cathode at each end of the device within the envelope. a resistor connected invseries with one-of'said cathodes, said resistor being positioned within the envelope adljacent its associated cathode, a pair of polarized terminal-pins at each end of the envelope, the respective cathodes being directly connected at one end to pins of `one type and the free ends of the-'resistor and oi the cathode remote therefrom being connected to pins of the other type, said-lampbeing adapted to insertion ina pair of polarized receptacles' so that during an initial starting; period the circuit extends through said cathOdes and said resistor in series and subsequently-to the initial period the circuit extends through said resistor and its associated cathode, and' thence throughl the arc discharge pathto the' opposite cathode, said'resistor having a potential drop per unitof length less than the breakdown Ypotential of the gaseous atmosphere per unit of length, said resistor being in lseries with the discharge path and serving to limit the current through .the lamp for` direct current operation. v

WALTER J. DREMANN. ROBERT E. DUNHAM.

References Cited inthe le ofthis patent UNITED STATES PATENTS Number Name Date 1,980,534 Kirsten Nov. 13, 1984 2,038,049` Kirsten Apr. 21, 1936 2,175,929 Stimson Oct. 10, 1989 2,248,979 Friederich July 15, 1941 2,295,043 Lompe Sept. 8, 1942 2,315,286- Hays Mar. 30, 1943 2,369,987 Sperti Feb. 20, 1945 2,497,512 Padrnos Feb. ,14, 1950 FOREIGN PATENTS Numberr Country Date 527,940 Great Britain Oct. 18, 1940 

